Drug Delivery to Ocular Tissues by the Instillation of Nilvadipine Nano-suspension：Comparison with Drug Behavior between Ophthalmic and Oral Administration

Abstract

We previously found that instillation of nilvadipine (NIL) nanosuspensions delayed the onset of lens opacification. In this study, we compared the NIL levels in lens, retina and blood of rat instilled with NIL nanosuspensions (71 nm) or orally administered with NIL suspension (21 μm). The NIL levels in lens and retina of rat instilled with 0.6% NIL nanosuspensions (30 μl) were similar to that of rat orally administered with 50 mg/kg NIL. On the other hand, the plasma drug level in NIL nanosuspensions-instilled rat was obviously less in comparison with orally administrated-rat (50 mg/kg). Moreover, the 0.6% NIL nanosuspensions did not affect the blood pressure, although, both systolic and diastolic blood pressures in the orally administrated-rat (50 mg/kg) were lower than those of normal rat. These results show that the instillation of NIL nanosuspensions are more useful as a topical ophthalmic drug delivery system than oral administration.